LAUSR

In this work, nonstoichiometric Cu2- xSe fabricated by a facile water evaporation process is used as high-performance Al-ion battery cathode materials. Cu2- xSe electrodes show high reversible capacity and excellent cycling stability, even at a high current density of 200 mA g-1, the specific charge capacity in the initial cycle is 241 mA h g-1 and maintains 100 mA h g-1 after 100 cycles with a Coulombic efficiency of 96.1%, showing good capacity retention. The prominent kinetics of Cu2- xSe electrodes is also revealed by the GITT, which is attributed to the ultrahigh electronic conductivity of the Cu2- xSe material. Most importantly, an extensive research is dedicated to investigating the detailed intercalation and de-intercalation of relatively large chloroaluminate anions into the cubic Cu2- xSe, which is conducive to better understand the reaction mechanism of the Al/Cu2- xSe battery.